We propose to investigate the structure and biologic functign of complex oligosaccharides which occur as integral components of mammalian plasma membranes and serum glycoproteins. To facilitate these studies we will utilize plant lectins which have the ability to recognize and to bind to specific sequences of sugars and to initiate a variety of biologic effects in various target cells. The principal objectives of our future work include the following: 1) To determine the structure of the oligosaccharide receptors for a variety of plant lectins so that these lectins can be used in a rational manner as probes of cell surface oligosaccharides. 2) To fractionate cell membrane glycoproteins from a variety of normal and malignant cell types by affinity chromatography on plant lectin-Sepharose columns and then to determine the number, distribution and structure of the oligosaccharide units of the glycoproteins. 3) To use plant lectins to select cell surface mutants of mammalian cells and to explore how these surface alterations affect the biologic properties of the mutant cells. 4) To explore the extent of the biologic activities of plant lectins and to attempt to correlate biologic activity with the particular carbohydrate binding site of the lectin. 5) To establish the structure of the carbohydrate units of selected serum glycoproteins and to determine whether these units have any biologic functions.